Thermal Airflow Measuring Device

ABSTRACT

In order to provide a flow measuring device high in thermal responsiveness, the flow measuring device includes a temperature detecting element 2 for temperature detection, and a conductive metal lead frame 3 that supports and fixes the temperature detecting element. Of the metal lead frame, a part of the metal lead frame mounted with the temperature detecting element has a portion which is thinner than the thickness of the other metal lead frame or narrower than the width of the other metal lead frame.

TECHNICAL FIELD

The present invention relates to a thermal airflow measuring device formeasuring the flow rate of air flowing through an intake air passage ofan internal combustion engine.

BACKGROUND ART

One of the most common methods of accurately controlling an air-fuelratio of an internal combustion engine is means for measuring an intakeair flow rate and an intake air temperature to sequentially calculate afuel injection amount at which a combustion status is optimal. A thermalflow measuring device is equipped with a flow rate detection unitincluding a heating resistor, a temperature detection unit including athermistor, and an electronic control circuit unit that controls theheating temperature of the flow rate detection unit. A knownconventional flow measuring device has a thermistor element fortemperature measurement disposed in an intake pipe of an internalcombustion engine to allow it to be hardly affected by heat from theinternal combustion engine in order to thereby achieve a cooling effectby intake air.

A structure with such a technique applied to includes a flow measuringdevice described in Patent Document 1.

RELATED ART LITERATURE Patent Document

Patent Document 1: JP-2008-292508-A

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

The challenge lies in ensuring high detection temperature accuracy of atemperature detecting element and thermal response thereof. This isascribable to the material and structure of the conventional temperaturedetecting element. A conductive member is used for conductive lead wiresbonded to both ends of a temperature detecting chip, and conductiveterminals or connector terminals supporting the temperature detectingelement having lead wires. A conductive metal material has higherthermal conductivity rate by one digit or more as compared to, forexample, a resin, and the heat of a resin housing of a flow measuringdevice body is transferred to the temperature detecting chip through ametal material, which causes certain amount of errors. Specifically, theheat is conducted through the metal terminal from the housing to thetemperature of the temperature detecting chip portion exposed to air andthe housing body via a coating film when the material is used in asteady operation. This temperature is in equilibrium to an actualtemperature to be measured. Further, in a transient period when thetemperature of the body housing and the intake air temperature at thestartup of an internal combustion engine are different mainly, heat sinkis slow if the heat capacity of each of the lead wire, terminal, andcoating film is large, which deteriorates the detection thermal responseof the temperature detecting chip.

An object of the present invention is to provide a flow measuring devicehigh in thermal response.

Means for Solving the Problems

In order to achieve the above object, a thermal airflow measuring deviceof the present invention is constructed as follows.

The thermal airflow measuring device includes a temperature detectingelement for temperature detection, and a conductive metal lead frame forsupporting and fixing the temperature detecting element. A part of themetal lead frame on which the temperature sensing element is mounted hasa portion thinner than the thickness of the other metal lead frame ornarrower than the width of the other metal lead frame.

Effect of the Invention

The present invention makes it possible to provide a flow measuringdevice high in thermal response.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of a sensor chip package.

FIG. 2 is a top view of the sensor chip package shown in FIG. 1.

FIG. 3 is a side view of the sensor chip package shown in FIG. 1.

FIG. 4 is a schematic structural view of lead frames and outer leads.

FIG. 5 is a schematic cross-sectional view of a sensor chip package.

FIG. 6 is a top view of the sensor chip package shown in FIG. 1.

FIG. 7 is a side view of the sensor chip package shown in FIG. 1.

FIG. 8 is a schematic structural view of lead frames and outer leads.

FIG. 9 is a schematic structural cross-sectional view of an air flowrate and a temperature measuring device.

FIG. 10 is a schematic side cross-sectional view of the air flow rateand temperature measuring device shown in FIG. 9.

FIG. 11 is an enlarged sectional view taken along line C-C of a portionA of FIG. 10.

FIG. 12 is an enlarged sectional view taken along line C-C of theportion A of FIG. 10.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described withreference to the drawings.

Embodiment 1

A sensor chip package 1 according to one embodiment of the presentinvention will first be described with FIGS. 1 to 3.

In FIGS. 1 to 3, a thermistor chip 2 for detecting the temperature, aflow rate sensor chip 8 and a control circuit chip 9 for detecting anair flow rate, and a lead frame 3 for supporting and fixing them toachieve an electrical conduction are implemented by way of soldering ora conductive adhesive. All the chips needed are joined by heating andcuring through the single step at earliest.

When the electrical conduction is not necessary between the back surfaceof the chip and each lead frame 3, an insulative, e.g., epoxy adhesivecan also be used for the flow rate sensor chip 8 and the control circuitchip 9 without the conductive adhesive.

Conductive metal materials such as a copper alloy, an iron-nickel alloy,and stainless steel are used for the lead frame 3. The lead frame 3 isformed by precision micro press molding or etching.

After the mounting of the thermistor chip 2, the flow rate sensor chip8, and the control circuit chip 9 to the lead frame 3, each sensor chipand the control circuit chip 9 are joined to each other with the use ofthin wires 12 such as gold, copper, and aluminum wires to achieve mutualelectrical conduction and wire-bonding them by a method such asthermocompression, ultrasonic vibrations, and ultrasonicthermocompression.

The lead frame 3 mounted with the thermistor chip 2, the flow ratesensor chip 8, and the control circuit chip 9 is covered by a transfermolding with the use of a thermosetting resin 5 in such a manner as toinclude them. A portion (called outer leads 4) of the lead frame 3required to achieve electrical conduction with the partial surface ofthe flow rate sensor chip 8 and the outside is transfer-molded so as tobe exposed from the resin 5.

The sensor chip package 1, the lead frame 3, and the outer lead 4 willnow be described in detail with the use of FIG. 4. The portion of theresin 5, which is thermally cured by the transfer molding, is shown in abroken line.

The lead frame 3 is preferably placed such that the side opposite to oneend to which the thermistor chip 2 is mounted is out of the surface thatis to be resin-molded. The lead frame 3 is configured to connect with anouter frame 6. The lead frame 3 can be seen to divide its role into; (1)a portion finally configured as a part of a product; and (2) a suspendedstructural portion required for manufacture, for connecting with theouter frame 6. In particular, the suspended structural portion of thelatter is called a tie bar 7.

The tie bar 7 is a part punched by the same press as the lead frame 3 orothers. The tie bar 7 plays the role of maintaining a shape in such amanner that when the electrical circuit is configured in themanufacturing process, the lead frame 3 does not come apart even ifdisconnected at required places. Then, after the transfer molding hasbeen completed with the use of the thermoplastic resin 5, the portion ofthe tie bar 7 is cut off following the lead frame 3 fixed by the resinso that the cut portions do not remain in the product other than the cutcross-sections.

The outer leads 4 for withdrawing a detection signal of each sensor chipto the outside are also similarly connected to the outer frame 6 via thetie bar 7, whereby the shape of each outer lead is maintained.

The lead frame 3 mounted with the thermistor chip 2 is formed by aprecise and fine pressing or an etching to a part of signal lines ofpositive and negative electrodes. The dimension of the lead frame 3 isconsequently configured to be thinner than the board thickness, narrowerthan the lead width, or both thinner and narrower.

An electric signal of the thermistor chip 2 is connected to the controlcircuit chip 9 by way of the thin wire such as the gold or copper wirethrough the lead frame 3, or is connected directly to the outer leads 4aside from the function of flow rate detection, followed by being outputto an external device.

The lead frame 3 mounted with the thermistor chip 2, the flow ratesensor chip 8, and the control circuit chip 9, and the thin wires 11 and12 having less heat capacity, such as a gold, copper, and aluminum wireare provided with a package structure covered with and protected by theresin 5 with a method like transfer molding, except for a part of thesurface of the flow rate sensor chip 8.

After the resin molding has been completed, the tie bar 7, which extendsout to the outer periphery of the sensor chip package 1, is cut off, andthe disconnected surface is sealed with an adhesive as needed, thusresulting in the sensor chip package 1.

The need for temperature measurement in an internal combustion engineand the structure of the temperature detecting element 2 will bedescribed here. The temperature measurement is also used for the optimumcontrol of the fuel injection amount according to fuel consumption in atransient period such as during a cold start, and suppression of harmfulsubstances in exhaust gas by catalyst temperature control in addition tothe application aiming at a restraint on the internal combustion enginein a steady state. A temperature detecting function for measuring thetemperature of air sucked by the internal combustion engine isessential. Therefore, a temperature detecting element 2 based on variousschemes and structures has been proposed and practically used widelytoday. A few of the known temperature detecting element 2 are atemperature measuring resistor including a thermocouple, a diode, andplatinum, and an element formed with a temperature sensitive resistor ona silicon substrate using a semiconductor micromachining technology. Oneof the methods of the technology is to detect the temperature from theresistance value of a thermistor where the thermistor is adopted as adetecting element. This thermistor employed for the temperaturedetecting element is configured as follows: a thermistor element havinga thermistor chip protected with various structures is placed in a flowpath through which air in the internal combustion engine flows; and thethermistor element is thereby electrically connected to the circuit inthe flow measuring device or to a connector terminal for a conduction toa fuel injection amount calculation unit (engine control unit). Thetemperature detecting element has been practical in these ways.

The thermistor element is bonded with lead wires such as a dumet wirehaving its adhesion to the soft glass improved by bonding copper to aconductive nickel alloy, a CP line (kappa-ply line) thick-plated bycopper with iron or steel as a core material in order to achieve anelectrical conduction with an external device across the thermistorchip, applying machining for diffusion bonding of a metal-to-metalinterface by press bonding, and generating copper suboxide on theoutermost surface. A cylindrical glass tube is covered to enclose theentire circumference of the chips and the junction between the chips andthe lead wires. The chip, lead wires, and glass are calcined to therebyfuse and contract the glass, so that the chip and the lead wires arestabilized. Alternatively, there is a structure where a glass tube isnot used; a temperature detecting element with its junction to the chipand the lead wires protected by coating-fixing of a thermosetting resinafter the chip and the lead wires are bonded by solder or othermaterials. It has been known that in the case of the dumet wire, thereis obtained a closer adhering structure by calcining the glass to meltthe glass and by chemically bonding the glass and cuprous oxide. Then,in order to place and support and fix the completed thermistor elementin the flow path of the internal combustion engine, each of theelement's lead wires is joined by welding or other methods to aconductive sheet metal-made terminal. For the purpose of the transfer ofan electrical signal to and from an external device, each conductiveterminal is connected directly or indirectly to a connector terminalthrough a separate conductive member such as an aluminum wire and anelectronic circuit board. The connector terminal is molded integrallywith an insulative housing body such as a resin to support and fix it.The thermistor element electrically connected via the conductiveterminals disposed in the housing body is also connected to the flowmeasuring device or the fuel injection amount calculating device (enginecontrol unit) through a connector disposed in the housing. In general, aconstant voltage is supplied to the thermistor element with the use ofthe corresponding connector terminal through at least one seriesresistor from the above device. When an inter-terminal voltage of thethermistor element, divided by the series resistor, is detected, theresistance value changes with the temperature change of the thermistorelement, whereby a detection voltage changes as well. It is thuspossible to obtain the voltage change as a temperature signal.

There are many cases in which the flow measuring device is used in arelatively harsh environment in an internal combustion engine such as anautomobile. For example, the flow measuring device is used under harshenvironments including corrosive gases generated under a fuel vaporatmosphere and high temperature environments, and water and salt waterscattering through an air cleaner filter. One of the temperaturedetecting elements based on an assumption to be exposed to the flow pathof the internal combustion engine is a glass-sealed thermistor elementserving as the temperature detecting element especially ensuresreliability by the followings methods: coating the interface (small gap)between the lead wires and the glass with the use of a resin with athermosetting property to prevent corrosion and electrolytic corrosiongenerated in the interface; sealing the junction between each lead wireand the conductive terminal with a thermosetting resin after solderingor welding, depending on the degree of additionally required durability;and using heat-resistant coated wires to prevent electrochemicalcorrosion developed between the lead wires having different polarity tothereby inhibit and protect short circuit defects due to water or saltwater between the lead wires. Since, however, the glass tube is placedso as to cover the thermistor chip itself and the junction between thethermistor chip and each lead wire, there is a limit to structuralcorrosion resistance with respect to an area larger than the diameter ofthe lead wire. A thermistor element, generally called an axial lead typeand having lead wires on substantially the same straight line in theaxial direction in terms of the positive and negative electrodes,encounters a difficulty in uniformizing a coating thickness of a glasstube end (fillet portion) caused due to the difference between thediameter of each lead wire and that of the glass tube. There is thus acase where the thickness of the fillet portion cannot be ensured enoughor corrosion is caused when the coating film is in a porous state, i.e.,is formed with pores in the film. On the other hand, in a temperaturedetecting element generally called a radial type and having two leadwires disposed in parallel in the same direction, a coating film isrequired since a short circuit between the lead wires occurs in a barestate of a dumet wire even if the adhesion to the soft glass isincreased with the use of the dumet wire to prevent micro crevicecorrosion in the interface between each lead wire and the glass. Thedistance between the lead wires, however, is short as it depends on thesize of the thermistor chip. It is thus difficult to form a coating filmhaving no gap between the lead wires. Further, in the case that requiresprocessing (forming) of extending the lead wire in the following step,there is a concern that damage can be given to the coating film appliedaround the lead wires. When a heat-resistance coated wire is usedinstead of the dumet wire, it is difficult to take completecountermeasures against the corrosion occurring in the small gap in theinterface between the coated wire and the glass tube.

In the configuration described in the present embodiment 1, since theentire periphery of the thermistor chip 2 and the lead frame 3 can becovered with the thin resin, it is possible to avoid the non-uniformityof the coating thickness of the glass tube end caused by the differencebetween the diameter of each lead wire and the diameter of the glasstube. The cracks caused by strains such as heat and vibrations appliedto the fillet portion can be averted as well, in comparison with thestructure in which the thermistor chip 2 is held with the glass tube andthe junction between the glass tube and each lead wire is covered with acoating film. It therefore is possible to improve the corrosionresistance.

The temperature detecting element also needs to take heat intoconsideration in addition to the corrosion resistance. The problemspecifically is an error between the temperature of the temperaturedetecting unit with the temperature detecting element mounted theretoand the actual temperature in the flow path of the internal combustionengine. The error could occur under the environments where: the flowpath wall is higher in air temperature than within the flow path due toreceiving radiant heat from the internal combustion engine; and the flowpath wall is at room temperature or under the low temperatureenvironment at the time of startup, yet the temperature in the flow pathis high. In order to minimize the temperature detection error even inany of the foregoing, the thermistor element has a structure activelysubjected to the air. The lead wires and the conductive terminals arefurther exposed to the air (heat release), thereby to reduce an effectby the temperature difference between the flow path wall and theinstallation part material of the temperature detecting element. Anothermethod for fewer temperature errors includes reducing thecross-sectional area of the member in order to suppress the heattransfer. It is however necessary for the flow measuring device or thetemperature detecting element to be designed to withstand variations anda temperature and humidity cycle in addition to the corrosionresistance, considering the installation environment of the flowmeasuring device or the temperature detecting element. Therefore, thetemperature detecting element includes a lead wire with dimensions ofapproximately 0.2 mm or more. Columnar and prismatic support terminalsfor supporting and fixing the detecting element also have largerdimensions than the one above. The temperature detecting element isinevitable from having a complex structure since another reinforcingmeans is structurally required to narrow the wire diameter or thecross-sectional dimensions.

However, in the structure described in the present embodiment 1, it ispossible to cover the whole circumferences of the thermistor chip 2 andthe lead frame 3 with the resin. It is therefore possible to thinly forma portion of the lead frame serving as the electrical signal line of thesame potential, which cannot be achieved because of insufficientmechanical strength in the glass tube, the junction between the glasstube and each lead wire, and further the structure of coating (to cover)and protecting the lead wire itself. Therefore, a decline in thecross-sectional area of the lead frame 3 curbs the conduction of thehighest heat conveyed from the outer leads 4 (metal) made of theintended conductive material. This leads to provision of a thermalisolating structure portion 10, which is capable of isolating thetemperature detected by the thermistor chip 2 from the heat of the bodysupporting the sensor chip package 1 and incorporating the same.

Thus, since the effects of heat conducted from the outside (internalcombustion engine) through the outer leads 4 and the housing 14 arerelaxed by the thermal isolating structure portion 10, the detectionfunction of the thermistor chip 2 is high in precision with less thermaleffects and better thermal response, thereby making it possible torealize a flow measuring device having high reliability.

Embodiment 2

Embodiment 2 which is an embodiment in the present invention will now bedescribed below.

FIGS. 5 through 8 sequentially correspond to the illustrated directionsshown in FIGS. 1 through 4, respectively, and show an example in whichthe method of the thermal isolating structure portion 10 previouslymentioned can be achieved by another means with respect to FIGS. 1through 4.

In FIG. 5, a lead frame 3 is formed by press molding or etching in sucha manner as to divide the middle of the positive and negative electrodesignal lines provided between the thermistor chip 2 and the controlcircuit chip 9. The lead frame 3 mounted with the thermistor chip 2 isstill in an electrically disconnected state at this time. In order toconfigure the electrical signal lines of the same polarity, the two leadframes 3 and 23 are subjected to wire-bonding-joint therebetween bythermocompression bonding, ultrasonic vibrations, or ultrasonicthermocompression bonding with the use of thin wires 11 low in heatcapacity such as a gold wire, a copper wire, and an aluminum wire. Thelead frame 23 having achieved the electrical conduction by way of beingconnected to the lead frame 3 mounted with the thermistor chip 2 and tothe thin wires 11 has a package structure covered with and protected bythe resin 5 by way of the method including the transfer molding in sucha manner to incorporate all the necessary chip components and goldwires. After the resin molding has been completed, a tie bar 7protruding to the outer periphery of the sensor chip package 1 is cutoff. The cut surface of the tie bar 7 is sealed with a resin or adhesiveand turns out to be the sensor chip package 1.

Thus, it is possible to completely separate the part of the lead frame 3corresponding to the electrical signal lines of the same potential,which cannot be achieved in the glass tube, the junction between theglass tube and the lead wire, and further the structure of coating andprotecting the lead wires. The divided lead frame 3 and lead frame 23can be configured without impairing the function as an electricalcircuit by being connected to the thin wires 11 having lower heatcapacity than the lead wires. It is possible to block the heat conductedthrough the lead frame 23 and the outer leads 4 due to the radiant heatof an intended internal combustion engine by a resin having higherthermal resistance than a metal member. It is further possible to obtainmore advantages of a thermal isolating structure that separates thetemperature detected by the thermistor chip 2 from heat of the bodysupporting the temperature detecting unit and incorporating the same.

Embodiment 3

An embodiment 3 that is an embodiment of the present invention will nowbe described below.

FIG. 9 is a schematic structural cross-sectional view of an airtemperature measuring device being in a state where the sensor chippackage 1 described in the embodiments 1 and 2 is attached to an intakepipe (duct) 13 for introducing air 18 to be taken in an internalcombustion engine. FIG. 10 is a schematic structural cross-sectionalview as seen from the side of FIG. 9.

In FIGS. 9 and 10, the sensor chip package 1 is bonded to and built in abody of a resin-made housing 14 that serves as a box-shaped insulatinghousing with the use of an adhesive, for example.

The housing 14 is provided with a function to surround the bottom andside faces of the sensor chip package 1 substantially over its entirecircumference as a case member for housing the sensor chip package 1 inorder to protect it. The housing 14 also has a connector (coupler) 15for transmitting and receiving electrical signals to and from anexternal device, the connector being formed, for example, by resinmolding. Conductive connector terminals 16 made of a copper alloy orother materials are insert-molded in the connector 15 with the use of athermoplastic resin.

The case member may be constituted by bonding and fixing a plate-likeresin or sheet-metal-made base plate to the bottom face of the housing14 as a separate member or by insert-molding the plate in the housing 14so as to be integrated.

The sensor chip package 1 mounted to the housing 14 is welded to each ofthe connector terminals 16 by ultrasonic vibrations with the use of analuminum thin wire 17 or other materials to set up an electric interfacewith an external device.

The electrical conduction can be achieved even by bending (formingprocessing) each of the outer leads 4 of the sensor chip package 1 bypress processing and joining it directly to the connector terminal 16with the use of a method such as spot welding, ultrasonic vibrationwelding, and laser welding.

In a method of nipping the plate-like terminal surface and each lead bywelding electrodes when welding and joining each of the connectorterminals 16 and the outer lead 4 and performing welding from the frontand back directions of the terminal surface, the bottom face of thehousing 14 could block the method, whereby the welding electrodes mightfail to be disposed. Therefore, a space in which all of the bottom faceof the housing 14 or the welding electrodes can be inserted should beopened in order that the connector terminals 16 and the outer leads 4may be welded. After they have been bonded, the base plate can beestablished as a structure even by being jointed to the housing 14.

The housing 14 may have a structure in which sub-passages 19 that takein a part of the air 18 passing through the intake pipe 13 is formed byresin molding and the sensor chip package 1 is protected from damagesuch as drop impact.

The housing 14 having mounted the sensor chip package 1 therein issealed with a plate-like resin-made cover 20 with the use of an adhesiveor joined to the housing 14 by way of a method such as laser welding,vibration welding, and ultrasonic welding.

The housing 14 sealed with the cover 20 is fixed with the use of screws21 or a method such as thermal welding in such a manner as to be locatedinside the intake pipe 13 through which the air 18 introduced into theinternal combustion engine flows.

The connector 15 integrated with the housing 14 is fixed to be locatedoutside of the intake pipe 13.

FIG. 11 is an enlarged sectional view taken along line C-C of a portionA shown in FIGS. 9 and 10. In the sensor chip package 1 mounted to thehousing 14, preferably, the thermal isolating structure portion 10provided in the lead frame 3 mounted with the thermistor chip 2 isarranged such that the thermistor chip 2 and the lead frame 3 areexposed to the tip side of the housing as viewed in the directionopposite to the connector 15 with the resin portion of the body of thehousing 14 as a boundary, and is disposed inside the housing resin 5.The lead frame 23 located on the side opposite to the lead frame 3equipped with the thermistor chip 2 with the thermal isolating structureportion 10 as a boundary is preferably placed in the direction on theside of a circuit chamber whose four sides are surrounded by the resinof the housing 14 body. Alternatively, the thermal conduction of themetal member can be reduced even if a part of the thermal isolatingstructure portion 10 is inside the range of the resin portion of thehousing 14 as long as the following condition is met; the signal linesof the lead frame 3 having electrically same polarity is structured tobe a reduced cross-section surface, or to be including a thin wire lowin heat capacity, i.e., to be thermally-separated.

As a result, the temperature detected by the thermistor chip 2 and theheat of the body for supporting and fixing the temperature detectingunit can be isolated. It is therefore possible to provide a flowmeasuring device having high temperature accuracy of air that theinternal combustion engine sucks, as well as high thermal response.

Embodiment 4

Embodiment 4 which is an embodiment in the present invention will now bedescribed below.

FIG. 12 shows a schematic cross-sectional view of the flow measuringdevice of FIG. 11 to which further improvements have been added.

Lead frames 22 each electrically disconnected between a lead frame 3mounted with a thermistor chip 2 and another lead frame 23 arranged insuch a manner as to form an electrical signal line of the same polarityand connected to a thin wire 11 are created by precision fine press workor etching simultaneously with an outer frame 6 (lead frame body)through a tie bar 7. The lead frame 3 and the lead frame 23 dividedafter the thermistor chip 2 has been mounted on the lead frame 3 arebonded to each other by the thin wire 11 and transfer-molded with theuse of a resin 5.

As a result, compared with the case where the part of the thermalisolating structure portion 10 provided in the lead frame 3 mounted withthe thermistor chip 2 has stiffness with only the resin 5 as thestructure, it is possible to further improve mechanical shock resistanceand vibration resistance because the metal material lead frames 22 arecontained inside the resin 5 and to isolate the heat conducted throughthe initially-targeted metal material, which thereby realizes the flowmeasuring device high in reliability.

REFERENCE NUMERALS

1 sensor chip package

2 thermistor chip (temperature detecting element)

3, 22, 23 lead frames

4 outer lead

5 resin

6 outer frame (lead frame body)

7 tie bar (lead frame suspension structure)

8 flow rate sensor chip

9 control circuit chip

10 thermal isolating structure portion

11, 12 thin wires

13 intake pipe

14 housing

15 connector (coupler)

16 connector terminal

17 aluminum thin wire

18 air (flow of air)

19 sub-passage (temperature sensor protecting member)

20 cover

21 screw

1. A sensor chip package, comprising: a temperature detecting element; afirst conductive lead frame extending between the temperature detectingelement and a thermal isolating structure portion of the device; asecond conductive lead frame electrically interconnected with butphysically separated by the thermal isolating structure portion from thefirst conductive lead frame; a circuit chip electrically connected tothe temperature detecting element and to outer leads, the temperaturedetecting element, the first conductive lead frame, the secondconductive lead frame, the thermal isolating portion, and the circuitchip being sealed by a thermosetting resin; and a physical quantitysensor element electrically connected to the circuit chip, wherein thetemperature detecting element is in contact with the first conductivelead frame, the thermal isolating structure portion is defined by thinwire having heat capacity below that of the first conductive lead frame,and the thin wire has smaller cross-sectional area than the first leadframe and the second lead frame.
 2. The sensor chip package of claim 1,wherein the temperature detecting element is a thermistor chip.
 3. Thesensor chip package of claim 1, wherein the thin wire is a wire-bonding.4. The sensor chip package of claim 2, wherein the thermistor chip isattached to at least the first conductive lead frame by a conductiveadhesive.
 5. The sensor chip package of claim 1, wherein the physicalquantity sensor element is a flow rate sensor chip.
 6. The sensor chippackage of claim 5, wherein the outer leads include at least one exposedouter lead.
 7. The sensor chip package of claim 6, wherein the flow ratesensor chip is sealed by the thermosetting resin so that the detectionpart of the sensor chip is exposed.
 8. The sensor chip package of claim7, wherein the second conductive lead flame is electrically connectedwith the circuit chip by a second thin wire and the second thin wire isalso sealed by the thermosetting resin.